1. What is API Gravity?

API Gravity is a measure of how heavy or light a petroleum liquid is compared to water. It was developed by the American Petroleum Institute (API) to standardize measurements of petroleum density. For jet fuel, API gravity helps determine fuel quality and performance characteristics.

2. How Does the Calculator Work?

The calculator uses the API Gravity formula:

Where:

• \( API \) — API Gravity (degrees API)
• \( SG \) — Specific Gravity (dimensionless)

Explanation: The equation converts specific gravity (the ratio of a fuel's density to water's density) into the API gravity scale.

3. Importance of API Gravity for Jet Fuel

Details: API gravity is crucial for jet fuel because it affects fuel density, energy content, and cold weather performance. Jet fuels typically have API gravities between 35° and 51° API.

4. Using the Calculator

Tips: Enter the specific gravity of the jet fuel (measured at 60°F/15.6°C). The specific gravity must be greater than 0.

5. Frequently Asked Questions (FAQ)

Q1: What is the typical API gravity for Jet A fuel?
A: Jet A fuel typically has an API gravity between 37° and 51° API.

Q2: How does API gravity relate to fuel density?
A: Higher API gravity means lighter (less dense) fuel. Lower API gravity means heavier (more dense) fuel.

Q3: Why is API gravity important for aircraft?
A: It affects fuel weight (range calculations), energy content, and cold flow properties.

Q4: What's the difference between API gravity and specific gravity?
A: API gravity is an inverse scale that increases as density decreases, while specific gravity decreases as density decreases.

Q5: At what temperature should SG be measured?
A: For accurate API gravity calculations, specific gravity should be measured at 60°F (15.6°C).